Pemphredon lethifer

Pemphredon lethifer (Shuckard, 1837)

Morphology

Adult: medium to small sized (6-8 mm), body completely black, well defined petiole, head "squared off" behind the eyes, wing with two submarginal cells.
  

Biology

The females, fertilized in spring, go prospecting for dry pith stems. Access to the medullary part is made possible by a break or natural accidental damage. The pith of living stems is never used. The first gallery is dug, to a maximum of about 20 cm. The first cell for storing prey is subsequently created at the end of this gallery, further ones being set up by going back upwards.
Once the first cell has been finished, the female collects aphids from the host plant, grasping them quickly between her mandibles. The prey is paralyzed in flight during transportation, then immediately taken into the cell that has already been prepared. The aphids are subsequently gathered progressively until the cell is full (around 60 aphids).
Just one egg is laid per cell, fixed onto one of the first prey collected. Each of the cells is closed up using a plug of sawdust produced from excavation of the next cel, which the female does at night, leaving time for hunting in the daytime. She can build a dozen cells in one nest. During her whole life, a female can harvest a good thousand or so aphids.
The larva then eats the aphids. Its ration finished, it overwinters and waits for spring before undergoing nymphosis. Two or three generations per year are possible. Invariably, the cells at the back of the nest (first eggs laid) produce females, whereas those higher up, (last eggs laid) form the males.

Habitat 

This Pemphredon is caulicolous: it makes its nest in stems of plants with soft, tender and dry medulla like brambles, elder, roses, reeds, even also in galls of Lipara lucens (on Phragmites) and galls of Cynipidae.

Prey

According to Janvier (1961) and Danks (1968), several species of aphids are victims of this predator.

 

 

Modification date : 07 February 2023 | Publication date : 31 January 2012 | Redactor : Evelyne Turpeau, Maurice Hullé, Bernard Chaubet